PSYCHE 
Vol. 87 
1980 
No. 3-4 
THE NATURAL HISTORY AND BEHAVIOR 
OF THE BOLAS SPIDER 
MASTOPHORA DIZZYDEANI SP. N. (ARANEIDAE) 
By William G. Eberhard 1 
Smithsonian Tropical Research Institute and 
Departamento de Biologia, 
Universidad del Valle, Cali, Colombia 
Introduction 
The unusual hunting techniques of the bolas spiders of the tribe 
Mastophoreae ( Mastophora, Dichrostichus, and Cladomelea) were 
described long ago (Hutchinson 1903, Longman 1922, Akerman 
1923). These spiders make a large sticky ball on the end of a short 
thread, and swing the ball at passing insects while hanging on another 
short, horizontal “trapeze” line. Probably because the spiders are 
difficult to find, however, little has been done since to solve the 
problems which these first observations raised. Gertsch (1955) gives a 
complete and clear resume of what had been discovered of the 
biology of the entire group to that date. 
A recent study of an undescribed species of Mastophora which 
included observations of the behavior of both the spider and its prey 
plus extensive series of prey has finally confirmed the suspicion of the 
early naturalists that Mastophora lures its prey with a volatile 
substance which mimics the sex attractant pheromone of virgin 
female moths (Eberhard 1977). The present paper gives a taxonomic 
description of the species on which this work was done and presents 
‘Present address; S.T.R.I. and Escuela de Biologia, Universidad de Costa Rica, 
Ciudad Universitaria, Costa Rica. 
Manuscript received by the editor December 22, 1980. 
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